The present invention relates to an airconditioning system utilizing a plurality of absorption chiller-cells for refrigerating a second coolant medium such as an anti-freeze solution to obtain a sufficient low temperature for the indoor fan-coil units of an airconditioning system, by circulating and exchanging heat of the second coolant medium gradually from the first absorption chiller-cell and through up to numbers of absorption chiller-cells in a consecutive order, for providing an accumulative chilling effect, to give more efficient and faster cooling.
Further the invention provides a method and apparatus for operating an absorption chiller-cell, utilizing an absorption refrigeration means which has a plurality of evaporator means. The apparatus employs multi-refrigerant circulation circuits in an absorption cycles so as to enable the physical size of the system to be smaller and the cooling capacity larger, when compared to existing absorption systems. This invention also provides an airconditioning system wherein absorption chiller-cells produce various different capacities by combining various numbers of chiller cells, chiller cells maintenance or replacement is easily accomplished.
Various systems have been devised before to make an airconditioning system utilizing an absorption refrigeration means. One known arrangement is to use water as the refrigerant and lithium bromide as the absorbent. However, this system is not suitable for home use due to its physical size and a complex construction required to solve the crystallization problem. There is also the risk of freezing due to the use of water as the refrigerant.
Another known airconditioning system uses a solution pair of ammonia as refrigerant and water absorbent. This system is relatively small compared to the system using LiBr (lithium bromide) and water, but still too big to replace the present electric airconditioning unit for home or apartment application. The main problem of the prior art absorption refrigeration cycle, is the technical difficulty in producing enough refrigerant at low temperature somewhat below that of the heat load with a small physical system. The prior art, including numerous patents and studies, is mainly concerned with the technology of improving the coefficient of performance (COP) of an absorption refrigeration system regardless of the physical size of the system. Conventional absorption refrigeration systems are not easily maintained or operated, and are therefore not adaptable for home applications.
An object of this invention is to provide an airconditioning system utilizing an absorption refrigeration means having a plurality of absorption chiller-cell structures for chilling a sufficient quantity of an antifreeze solution to a sufficient low temperature for the fan-coil units of an airconditioning system. Another object is to provide a method and apparatus for operating an absorption refrigeration system having a plurality of evaporators that provide an improved cooling capacity with a limited physical size refrigeration system. Still another object is to provide an absorption refrigeration system having a reduced physical size whereby the system can replace the cooling unit of the conventional electric airconditioning system for home use. Still another object is to provide an air conditioning system which is capable of increasing or decreasing its cooling capacity by increasing or decreasing the number of chiller-cell units to produce various different airconditioning system capacities. Still another object is to provide an absorption airconditioning system which will be easier to maintain and repair.
The outstanding characteristic of the invention is that the refrigerating means comprises a plurality of absorption chiller-cell structures for refrigerating an antifreeze fluid to sufficient low temperature; the anti freeze fluid is circulated through each absorption chiller-cell in consecutive order, to produce enough refrigerant volume to meet the cooling capacity requirements of the air conditioning system.
Another outstanding characteristic of the invention is to provide an airconditioning system based on the diffusion absorption (DA) cycle by employing multi-refrigerant circulation circuits in an absorption cycle. The DA technology is based on the Platen-Muntecs cycle and is currently manufactured internationally for hotel room and recreational vehicle refrigerators. The unique features of the new technology are (1) it can be gas-fired with no electric input required and (2) machines based on a DA cycle are essentially silent. Until the present invention it was thought that the DA cycle should consist of one refrigerant loop circuit, one solution loop circuit and one gas loop circuit; the single loop arrangement is not suitable for airconditioning systems due to its poor cooling capacity. The present invention employs multiple loop technology, i.e. multiple evaporators and multiple condensers.
Another unique characteristic of the invention is the method of heat exchange between an antifreeze and each absorption chiller-cell, employing tube-in-tube principles to create a plural evaporator and associated heat exchanging chambers. The antifreeze solution exchanges heat with the evaporating refrigerant by flowing as a liquid film along the outside surface of each evaporator tube. The temperature and volume of the antifreeze solution is controlled by using multiple evaporators in parallel flow relation, and passing the antifreeze solution in serial fashion through separate heat exchangers associated with the respective evaporators, whereby the antifreeze solution is cooled in stages.